The present invention relates to submersible well pump assemblies used to produce hydrocarbons from oil and gas wells. More particularly, the present invention relates to the specific manner in which the various components of a submersible well pump assembly are joined.
Submersible well pump assemblies generally include a pump to propel well bore fluid and a motor to drive the pump. Centrifugal pumps have an equalizer or seal section to isolate the lubricant fluid in the interior of the motor compartment from the well bore fluid while equalizing pressure between the well bore fluid and the interior of the motor compartment. Other components may also be included in appropriate subsurface environments such as a gas separator, and in the case of a progressive cavity pump, a gearbox that reduces rotational speed.
Prior submersible well pump assemblies typically are joined by bolts using flanges. A disadvantage of such a connection is the difficulty of making the necessary connection out in the field. The entire assembly must by assembled in a piecewise fashion while on the drilling platform. Aligning the flanges and inserting and securing the bolts can be a cumbersome and time-consuming procedure, particularly in cold or harsh weather.
Another disadvantage concerns the restriction in fluid flow caused by the flanged joint. The open space of a well bore of a producing well generally is limited by the inner diameter of the casing. Thus, the outer diameter of the submersible well pump assembly must fit within that inner diameter. Where a flanged connection is made, the diameter of the internal flow passage for well bore fluid is necessarily reduced to accommodate the width of the flange lip. The narrowed passage reduces throughput and can accelerate the wear rate of end connections, particularly when abrasive fluids are being pumped.
The present invention comprises a submersible well pump assembly having at least two housings, a clamp ring, and at least one anti-rotation member. The first housing has an end having an outer surface, an end face, and a shoulder on that outer surface. The second housing has an end having an outer surface and an end face. The outer surface of the second housing has external threads formed thereon and the end face of the second housing abuts the end face of the first housing.
The clamp ring is rotatably and slidably carried on the first housing and has internal threads that engage the external threads of the second housing. The clamp ring also has an internal shoulder that engages the shoulder of the first housing. To keep the connection secure, the assembly has at least one anti-rotation member having a cooperative element on each end of each housing to inhibit rotation of one housing relative to the other.